The hot spring snake, Thermophis baileyi, is endemic to the Tibetan Plateau and restricted to a few high altitudes locations, above 3500 m. The species has been recovered as the only Eastern Hemisphere member of the otherwise Western Hemisphere Dipsadiade. In a forthcoming article, Sylva Hoffman of the Institute of Clinical Molecular Biology, Christian-Albrechts-University, in Kiel, Germany suggests that Thermophis' preference for habitats with hot springs might be adaptation to the cooling climate during the uplift of the Tibetan plateau. She proposes that some of the thermal sites may have been free of ice during the last glacial maximum and acted as refuges for the snake. To test this, microsatellites and mitochondrial DNA were obtained from 153 individuals at 12 sites across the plateau. The results suggest that T. baileyi has at least two genetically diverse clades in Tibet, which developed during the Pleistocene and expanded after the last glacial maximum. Thus, the existence of separate glacial refuges on the central plateau can be assumed. Analyses of the genetic variation indicated a high level of geographic differentiation and population structure on a regional as well as on a rangewide scale. The study shows that, apart from the phylogeographic signatures, the diversiﬁcation of current Thermophis populations is caused by a limited dispersal due to mountain ranges, a strong preference for hot springs and the insular distribution of suitable habitats on the plateau.
Sylvia Hoffman. 2012. Population genetic structure and geographic differentiation in the hot spring snake Thermophis baileyi (Serpentes, Colubridae): Indications for glacial refuges in southern-central Tibet. Molecular Phylogenetics and Evolution http://dx.doi.org/10.1016/j.ympev.2012.01.014